Literal constants may be written by using an external representation of the data. In general, the external representation must be quoted (see Quoting); but some external representations can be used without quotation.
     "abc"                                   ⇒  "abc"
     145932                                  ⇒  145932
     #t                                      ⇒  #t
     #\a                                     ⇒  #\a
   The external representation of numeric constants, string constants, character constants, and boolean constants evaluate to the constants themselves. Symbols, pairs, lists, and vectors require quoting.